1. Field of the Invention
This invention relates to a new and improved Fresnell lens and filter for use with computer screens. More particularly, it provides a conveniently adjustable positioning device for a magnifying lens and a filter against harmful rays emanating from a computer screen. The device may be attached to the top of a computer screen cabinet and may be adjusted in position toward and away from the screen and also adjusted so that the filter and lens are interposed perpendicular to the line of sight from the viewer's eye to the screen. Provision is also made for pivoting the screen out of the field of view as required.
2. Background of the Invention
Adjustable lens holders for use with computer visual displays are shown in a number of patents. U.S. Pat. No. 4,529,268 shows a means for adjustment wherein a much more complicated and expensive lens port is required. Lenses and filters for screens are shown in such U.S. Pat. Nos. as 3,418,426 and 4,253,737. The use of a Fresnell lens is also shown in U.S. Pat. No. 4,051,535 and U.S. Pat. No. 4,309,074. An anti-glare panel and assembly for mounting the same on a screen is shown in U.S. Pat. No. 2,427,264. A Fresnell lens with a filter is shown in U.S. Pat. No. 4,493,535. None of the references cited in this paragraph has the flexibility of adjustment which is illustrated herein and described in the following portion of the text of this specification.